"I pulled out to go to the grocery store (Wednesday) morning and just the entire street was just covered in police officers and everything was taped off," neighbor Laura Boykin said.

Police did not release the identity of the caller, but her shaky voice can be heard describing what happened.

The caller told the 911 operator that Tobiassen picked her up and took her back to his apartment, where he told her he wanted her to see something.

"He opened up the shower, and there was a body in there," the caller said.

Police said Longo had been stabbed to death by Tobiassen, who was his roommate.

Investigators said they haven't determined the motive for the killing.

The caller told the operator that she screamed when she saw the body and left the bathroom. She said Tobiassen drove her home.

"Thank God he brought me home," the caller said. "But he's like, 'You're the only person that knows about this. If this gets out, I know it's you,' and I'm scared. He knows where my mom lives. He knows where I live."

Tobiassen is being held at the Palm Beach County Jail.

A Ford pickup truck was seen being towed from the area, but it's not known how the vehicle is connected to the investigation.